Medical Oncologist
CION Cancer Clinics
RET in the family: who to test, and in what order | CION Cancer Clinics
Once one person carries a RET fault, their parents, brothers, sisters and children can be tested for that exact change with a simple blood or saliva test. Each close relative has a one in two chance of carrying it. This page explains who should be tested, in what order, how children fit in, and what a negative result really means for them. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- Who in the family should be tested for RET?
- In what order should relatives be tested?
- What happens when a relative decides to be tested?
- Family testing terms, in plain language
- What a relative's result changes
- What this page cannot tell you
- Four things families say about testing relatives
- Common questions about testing the family for RET
The short answer
Who in the family should be tested for RET?
Every parent, brother, sister and child of a person who carries a RET fault should be offered a test. Each of them has a one in two chance of carrying the same change. Testing then moves outward along the side of the family the fault came from, one relative at a time.
Start with the person who has the cancer
The first test is usually done on the relative with medullary thyroid cancer, because it looks at the whole gene. Once their exact change is known, everyone else is tested for that one change only. If that relative has died, a stored tissue block from their old surgery can sometimes still be tested.
Why RET family testing is different
With most inherited cancer genes, children wait until adult life to be tested. RET is one of the clear exceptions. Thyroid cancer can begin in childhood, and early preventive surgery protects a child who carries the fault. So young children are included in the family plan from the start, at an age set by the family's variant.
How to raise it with relatives
Keep the first message short and factual. Say which gene was found, that a simple test can show who else carries it, and that early action works well. Avoid blaming the parent it came from, because nobody chose their genes. In many families an elder or a doctor in the family carries the message best. The counsellor can join a family video call if that helps.
A relative who does not carry the family change cannot pass it on. Their children need no RET test at all.Who comes first
In what order should relatives be tested?
The order saves money and worry. Each result tells you whose test is needed next and whose is not.
Parents
Testing both parents shows which side of the family the fault came from. That tells you which aunts, uncles and cousins also need to hear about it. A parent who carries it also needs their own adrenal and thyroid checks, even late in life.
Brothers and sisters
Every full sibling has the same one in two chance. Adult siblings who test positive usually need the same adrenal and thyroid plan straight away. Siblings who test negative can stop there, along with their children.
Children
Children of a carrier are tested early, at an age set by the family's variant. For the highest-risk change that means in infancy.
The counsellor plans
- When each child is tested
- Who explains the result to them later
The wider family
Aunts, uncles and cousins on the carrying side come next. In large joint families this can mean many people, so the counsellor helps you decide who to approach first.
Not sure whether this applies to you?
Ask an oncologistHow it works
What happens when a relative decides to be tested?
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The carrier shares a family letter
The counsellor gives the first carrier a short letter naming the gene and the exact change. Relatives take it to any genetics clinic, in Hyderabad or elsewhere.
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Each relative sees a counsellor
They hear what a positive or negative result would mean for them before giving a sample. Nobody should be tested without that conversation.
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A blood or saliva sample is taken
The laboratory checks only the known family change. This targeted test is simpler and usually costs less than testing the whole gene.
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The result is explained in person
A counsellor goes through it face to face or by video, never as a bare report on WhatsApp.
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Carriers join the RET plan, others stop
Carriers begin adrenal and calcitonin checks and plan surgery. Relatives who do not carry the change need nothing further for RET.
Words you will hear
Family testing terms, in plain language
- Cascade testing
- Testing relatives one step at a time, starting closest to the carrier and moving outward.
- First-degree relative
- A parent, full brother or sister, or child. Each shares half their genes with you.
- Targeted test
- A test for one known family change only, instead of reading the whole gene.
- Dominant inheritance
- One faulty copy is enough to raise risk. A carrier passes it to each child with a one in two chance.
- New fault
- A change that started in one person and was not inherited from either parent. Doctors call this de novo.
- Carrier
- Someone who has the fault. With RET, carriers need regular checks and usually preventive thyroid surgery.
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Side by side
What a relative's result changes
Carries the family change
Does not carry it
Thyroid surgery planned by the variant
No thyroid surgery needed for RET
Calcitonin and adrenal checks begin
Ordinary health care only
Each child has a one in two chance
Children cannot inherit it from you
Pregnancy planned with the team
No RET steps in pregnancy
Own children and siblings are offered tests
Your branch of the family can stop here
Being straight with you
What this page cannot tell you
It cannot tell you how your relatives will react, or decide for them. Every adult chooses for themselves whether to be tested. Some take time, and some say no. A counsellor can help you share the news gently and leave the door open.
It cannot tell you what your family's variant means
The exact change decides how early children are tested and when surgery is advised. What your specific variant means is a question for the counsellor who ordered the test. If no one in the family has been tested yet, the first test is a full gene test, not a targeted one.
Who this does not apply to
Relatives of someone whose RET change was found only in a tumour, such as a lung cancer, do not need testing. That change is not inherited and belongs under targeted therapy. Relatives of someone with the common papillary thyroid cancer do not need a RET test either.
Worried about a relative who lives in another district? The family letter works at any genetics clinic in India.Commonly believed
Four things families say about testing relatives
"My sister tested negative, so I must be negative too."
Each brother and sister has their own separate one in two chance. One sibling's result says nothing about another's. Each needs their own test.
"This is a women's problem. The men can skip it."
RET affects men and women equally. A father passes it on as easily as a mother. Leaving the men out is a common reason the pattern is missed.
"Our children are too young to be tested."
For RET, early testing is the standard advice. Thyroid cancer can start in childhood, and knowing early lets surgery be timed before it does.
"Even with a negative result, she should have scans every year."
If a relative tests negative for the known family change, their thyroid risk is the same as anyone else's. Extra RET checks are not needed.
Questions we are asked
Common questions about testing the family for RET
Who pays for testing relatives?
Each relative's test is usually billed separately. A targeted test for a known family change generally costs less than the first full gene test. Ask the clinic for a written estimate, and check whether any scheme covers it.
Can relatives abroad or in other states be tested?
Yes. The family letter names the gene and the exact change, and any accredited genetics laboratory can test for it. Relatives should still see a counsellor locally before and after the test.
My parents both tested negative. How did I get it?
The fault may have started new in you. This is common in MEN2B. Your brothers and sisters are then at low risk, though testing them is still reasonable. Your own children each have a one in two chance.
What if a relative refuses to be tested?
That is their right as an adult. Give them the family letter and let them know the offer stays open. If they have young children, gently explain why the children's safety depends on knowing.
Does a relative need a thyroid scan before the gene test?
No. The gene test comes first. It decides whether scans and calcitonin tests are needed at all. A carrier then starts those checks, and a non-carrier does not need them for RET.
Should my husband or wife be tested?
Not for your family's RET change. They are not related by blood, so they cannot carry it through you. Your children's chance comes only from the parent who carries the fault.
Can the whole family be tested on one visit?
Often, yes. Many families arrange one counselling session and take samples the same day, which saves repeat travel. Each adult still gives their own consent and hears their own result.
Where do we start?
Find the first carrier's report and the family letter. Then list parents, siblings and children on the carrying side. Call the CION helpline if you need help arranging counselling for several relatives together.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
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Sources
- GeneReviews (NCBI) — Multiple Endocrine Neoplasia Type 2
- National Cancer Institute — Genetics of Endocrine and Neuroendocrine Neoplasias (PDQ)
- MedlinePlus Genetics — Multiple endocrine neoplasia
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
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Talk to us
Need to arrange RET testing for several relatives?
Tell us who has been tested and who has not. We will help you plan counselling and samples so the family can travel once where possible. One helpline serves every CION centre.